Answer
Parent function: $y=sinx$
Transformation: $y=sin(\frac{1}{2}x)$
See the image below.
Work Step by Step
We can easily determine that the parent function is $y=sinx$ (Blue line graph on the image)
Then we apply the transformation:
To graph $y=sin(\frac{1}{2}x)$, we have to stretch the parent graph by the factor of 2 (Red line graph on the image).
